1. Field of the Invention
This invention relates to a novel alkaloid compound which is useful as a chemotherapeutic agent for the remission of leukemia in animals.
2. Description of the Prior Art
A number of leguminous plants belonging to the genus Sesbania are notorious for the toxicity of their seeds. These species, including S. vesicaria, S. punicea, and S. drummondii, having been linked to the poisoning of the livestock and poultry in the Southern Coastal Plain of the United States [J. M. Kingsbury, Poisonous Plants of the United States and Canada (1964), pp. 353-357]. Seeds of S. drummondii, also known as coffeebean, rattlebrush, and rattlebox, are reportedly characterized by a minimum lethal amount for sheep of about 0.1% of the animal's weight. Efforts to identify the toxic principle of these species have led to isolation of a variety of saponins and sapogenins, none of which has been documented as being toxic. A sapotoxin isolated from S. drummondii (Daubentonia longifolia) has been claimed as a contributing factor [A. Robey, "Isolation of the Toxin of Daubentonia longifolia," Thesis, Texas A&M Coll. (1925)].
In a search for chemical compounds which are chemotherapeutically active against leukemia systems, the three toxic species of Sesbania named above were screened by Powell et al. [Planta Med. 30(1): 1-8 (August 1976)]. For each plant, an ethanolic seed extract tested positive against lymphocytic leukemia P388 (PS) in mice. Certain enriched fractions were obtained from the seed extract of S. vesicaria, but the responsible agent or agents were not successfully isolated, identified, or obtained in a therapeutically acceptable form.
Powell, U.S. Pat. No. 4,200,639, now disclaimed, succeeded in isolating the tricyclic compound sesbanine from S. drummondii. Apparent activity in the KB cell screen and in the PS tumor system attributed to sesbanine in the patent disclosure was subsequently established to be the result of a heretofore unidentified impurity in the assayed fractions.